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Mineral resource-based cities have formed a large number of goafs due to the long-term mining of coal. It is of great significance to make full use of the abandoned land resources above the goaf to promote the transformation and development of resource-based cities. In order to avoid the threat of surface residual deformation to the proposed construction project, it is an urgent problem to obtain the stability results of the construction site accurately. First of all, based on the principles of relevance, hierarchy, representativeness and feasibility of index selection, 10 indexes are selected to construct the stability evaluation index system. Then the subjective weight and objective weight of evaluation indexes are determined based on improved AHP, rough set and CRITIC methods, which improves the accuracy of the determination of the index weights. In addition, the membership degree of each index is determined using the cloud model. Finally, the stability grade can be obtained according to the maximum membership degree theory. The above researches are applied to evaluate the stability of the Mianluan expressway construction site, and the results show that the stability level of the study area is not uniform and that there are two states: stable and basically stable. Finally, a sensitivity analysis of the subjective weight of each index is carried out, the index stopping time has the highest sensitivity to weight (12.44%), which is far lower than the corresponding weight change rate of 100%, indicating that the determination of weight is scientific and reasonable. These things considered, the reliability of the evaluation result is indirectly verified according to the field leveling. This research can provide a reference for the effective utilization of land resources above an old goaf. [ABSTRACT FROM AUTHOR]

Topographic relief is a key factor limiting population distribution and economic development in mountainous areas, especially in the transition zone from mountains to plains. Taking the southern Anhui mountainous area as an example, based on the digital elevation model (DEM) with a resolution of 30 m, we used 'quadratic' mean change-point analysis to calculate the optimal statistical unit, and then extracted the topographic relief. Taking the county as the unit of analysis, two indicators of population density and economic density were selected. Spatial statistics and correlation analysis were used to quantitatively analyze the impact of topographic relief on population and economy. Finally, the impact of slope and elevation was analyzed. The following results were obtained. (1) The topography of the study area was dominated by medium relief (200–500 m), followed by small relief (70–200 m), flat (0–30 m), and slight relief (30–70 m), and a small proportion of large relief (≥500 m). (2) The impact of topographic relief on population and economy was slightly stronger than that of slope and elevation. The impact on population distribution was stronger than that on economic development. The impact on primary industry was stronger than that on secondary and tertiary industries. (3) In the southern Anhui mountainous area, 72.35% of the population and 76.72% of GDP were distributed in the area with a topographic relief of 155 m or less, while the land area only accounted for 43.93%. The area with a topographic relief greater than 245 m accounted for 28.76%, but only 10.69% of the population, and only 8.34% of GDP. The population distribution and economic development were obviously concentrated in the low topographic relief area. However, the characteristics of high topographic relief not only hindered the agricultural mechanization and limited the development of the primary industry, but also had a significant impact on infrastructure development, investment, and industrial layout, thus weakening regional economic advantages. In the future, the economic level of these areas needs to be improved. [ABSTRACT FROM AUTHOR]

In recent years, more and more expressways pass through the abandoned coal mine, while the surface residual subsidence of the abandoned coal mine threatens the operation safety of the expressway. It is of significance to evaluate the stability of the construction site and take reasonable managements for effectively guaranteeing the traffic safety. How to accurately evaluate the stability of the construction site is the primary problem. This study proposes a stability evaluation model using the overlay and index method and points out that the evaluation scores and weights of evaluation indices are key parameters to determine the reliability of evaluation results. To reasonably determine the evaluation score, the scoring criteria of qualitative indices is obtained by the equidistant method, while the scoring criteria of quantitative indices is obtained by establishing scoring functions. The weights of evaluation indices are got by adopting the FAHP (fuzzy analytic hierarchy process). Then the built model is applied to evaluate the stability of the Wuyun Expressway construction site, and the results show that the Wuyun Expressway construction site is basic stable. Finally, the sensitivity of indices weights on the evaluation result is analyzed with the maximum C k (C m , p c) of 5.9% far lower than the weight change of ±30%, and the average residual subsidence velocity of the maximum subsidence point is 0.0456 mm/d using a high-resolution leveling, proving the credibility of the proposed model. Research results provide new ideas and systematic technical references for the stability evaluation of the construction site above an abandoned coal mine. [ABSTRACT FROM AUTHOR]